Process and apparatus for making composite glass



J. H. SHERTS April 25, 1933.

PROCESS AND APPARATUS FOR MAKING COMPOSITE GLASS Filed Aug. 11, 1950 4 Sheets-Sheet l J. H. SHERTS April 25, 1933.

PROCESS AND APPARATUS FOR MAKING COMPOSITE GLASS 4 Sheets-Sheet 2 Filed Aug. 11, 1950 T l m I a. m,

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ELMQ JT J. H. SHERTS April 25, 1933.

PROCESS AND APPARATUS FOR MAKING COMPOSITE GLASS Filed Aug. 11, 1930 4 Sheets-Sheet 5 J. H. SHERTS April 25, 1933.

PROCESS AND APPARATUS FOR MAKING COMPOSITE GLASS Filed Aug. 11, 1930 4 Sheets-Sheet 4 NVENTOR WM. mm

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Patented Apr. 25, 1933 UNITED s'raresf eA-re JAMES E. snnit'rsor nnacmmnea rEmisYLvANiA, AssIeNon ronnrLA'r -feon- PORATION, A COBPORATIQN or DELAWARE PROCESS AND fl es r comrosrrnenhssf' Application ni'erixii useri, 930. strain 474.376.-

The invention relates to a process and; apparatus for making composite or safety glass, which glass ordlnarllycompri'ses twosheets of glass cemented to the opposite sides of a sheet of reinforcing material, such as pyroxylin plastic (celluloid). The composib ing operation: requires heat and pressure in order to insure a proper u-mon between: thesheets, the heat' serving to softenthe plastic-i sheet slightly, so that the pressure 'iseifective 'to bring the opposing sur faces'1=nt o intimate contact and remove any irregulari: ties in the surface of theplastic. The heat also serves to make thecement'sticky when such cement-"has been allo'wedto dry upon the sheets preliminary-to (jomposltlfig as isordinarily the case where gelatin,'ca;sein or similar cements are employed. The deg ree of heat and pressure will vary-depending 30 on conditions,but' the pressure" will most cases range from 80--to?15O 'pounds '1per' square inch and the heat appliedfwill bel such as to bring the plastic toatemperat'ur'e of 200 degrees F. or sl1ghtlylmore: --1he present invention is designedtoprovide an improved means and apparatus for apply ing the necessary heat and pr'essure in: orderto composite the sheets which is continuousin its operation and requires a minimum of- Certain embodiments ofv the invention are illustrated in-the accom veyor 161's shown in alignment withthe-end time and labor.-

panying drawings, wherein:

Figure 1 is a vertical section through t he apparatus on the line I -I ofFig. 2;. Fig.

2 is a vertical section through the apparatus. on the line IIII of Fig. 1. F1'gs 3 4 and 5 are enlarged detail sections through the apparatus, Fig. 3 being a sectlonon the line IIL-III of Fig. 4, Fig. 4 being a section on the line IVIV of Fig.3, and Fig. 5 being a section on the line V+V of Fig. 13.

Fig. 6 is an enlarged detail sectionthrou'gh one of the trays or containers employed Fig. 7 is a view similar to Fig 6 through a modification. And Fig; 8 1s asection through another modification. i

Referring to the general arrangement of;- the parts as shown in Figs. -1 and 2,1 is an endless conveyor made up of two chains and carrying a: series of'traysor containers cleaned and provided 2 such chains'passing around the series of sprockets" 3, 4 and 5; 6- is a vertical' well.

carrying a bath. of mercury 7 inits lower portion and a bath 8 of a lighterhquid in its upper portion into which well'a series of containers 2 are lowered and removed by the conveyor; 9 is a motor by means of which the shaft carrying the sprockets 3 is-driven through the intermediary of certai'n reduction gearing; 10' is an exhaust hood located above the horizontal flightof V the conveyor; 1111 are steam pipes by ineansofi which the mercury in the lower portioir of the well 6 is heated; 12 is a sump into whichthe well may be drained; 13- is a drain pan over which the containers p'ass after their movement from the well above which are located washingsprays 14 and drying sprays 15; and 16' is the end or a conveyor table for bringing the as sembled sheets to a position=adjacent the conveyor 1'. y

In carrying out the operation,the sheets of glass to beused in the composite plat'es are with a coating of cement on oneside, upon the conveyor 16",, and,

a sheet of'pyroxylinplastic, such as celluloid I is placed 'between each pair of glass sheetsso that a series of sets of three sheets are de-- livered upon the end of the conveyor l6 ad jacent the conveyor 1. The end of the 'conk of the conveyor 1', but may be placedin'an'y" suitable position to permit the'operators to conveniently transferthe sets of sheets-to the containers 2' of the conveyor -The' sheets of glass are preferably cleaned uponwell 6 and then moved upward therefrom,

the direction of movement of the conveyor 1 being indicatedby the arrows; During thisperiod at movement through the well 6-, the

.sheets substituted preliminary to repeating sets of sheets are subjected to heat and pressure, the pressure being due to the hydraulic pressure in the well incident to its depth and being sufficient to composite the plate. If

merelypreliminary pressing is desired giving approximately 80 pounds per square inch, the column of mercury is made about 12 feet deep and is capped with a column of lighter liquid 8, such as diethylene glycol, about 6 feet-deep. For completepressing giving ap "proximately a pressure of 160 pounds per the cyclehe construction of the lower portion of Y the well 6, which is designed tocarry and heat the mercury 7, is preferably as indiv cated in Fig. 4. The sides of the well comprise .thesteel plates 16, 16 to which are welded the transverse channels 17 surrounded by the insulating material 18. The channels17 provide passages for steam for heating the mercury bath. The steam'is supplied by the pipes 11 which are connected to the passages19 formed betwen the channels and the plates 16. The series of passages are; all; connected together by means 'of the vertical passages '20. so that a circulation of: steam is provided on each side of the well fromthe upper steam pipes 11 to the lower steam pipes. In this manner the mercury -.is maintained at a temperature of about 240 degrees F. The mercury chamber is pro-.

vided. at its edges with a pair, of guides .21, 21 for receiving the chains of the conveyor 1 and also with the vertical spacers 22,- 22 for separating the two vertical flights .of, eacht V out the frame, the cover shown in Fig. .6

chain.

7 The conveyor 1 is made up of the chains 23, 23 (Figs. 3 and 4) connected at intervals by. the brackets 24, 24 mounted upon the edges of, the trays or containers 2. The

' sprockets 3 which drive the conveyor are mounted upon a shaft 25 to which is keyed the spur gears 26. The gears 26 are driven from the gears 27 on the shaft 28. The shaft 28 also carries a worm wheel which is driven from a worm 29, such worm being driven from the motor 9 through the intermediary of the chain 30 passing around sprockets on the shaft of the worm and the motor drive shaft. The two vertical flights of the chains whichpliein the well 6 merely turn back upon each other at their lower ends, as indicated; in Fig. 4, sothat no sprockets are.

required at this point, thus permitting. the well to be .made of a-minimuin width. The

posited, suchsheets comprising the pair of glass sheets, with an interposed reinforcing sheet with' the opposing faces of the sheets prepared for adhesion upon the application of heat and pressure. A closure for the container isprovided in the form of the thin sheet of rubber 34 secured along one edge totheplate2 by means of the binding strip 35.. Means are provided for exhausting the air from the space beneath the sheet 34 in the form of the exhaust pipe 36 having the 'valve37 atits end. This pipe commun cates with avacuum box 38 which in turn communicates with the space beneaththe cover 34 bymeans of the connection 39. After each, set of sheets is placedin the container and thecover 34 is applied, an exhausting device is connected at 37 and theair in the container .and in the box 38'is. exhausted. The useof the box 38 isadvantageous as it assistsfin. maintaining vacuum even though a slightleakageoccurs beneath the cover. 34.

The application of vacuum to e the container before; the, pressing operation facilitates such pressing operation as it tends to remove any air: which: is entrapped between the opposing surfacesqof the sheets to be .composited.

. Fig. 70f the drawings illustrates a mothfication in' which the flexible sheet 34 is carriedby a rectangular .frome 40, hinged at. 41to the plate 2 and provided with a handle 42. to open than the cover shown-in Fig. 6 withbeing preferably removed, to expose the set ofsheets by rolling it back upon. itself. r

\In operation, the conveyor 1 is moved at a rate of speed such that the cycle of immersion of the containers in the well 8 isabout 1O mi'nutesin case a complete pressing operation is desired, the operation of the conveyor preferably being a continuous one. This rate of movement gives plenty of time for the operators-to unload the containers when theyv reach the horizontal flight of the conveyor and to reload them with sets of sheets to be compo'sited. After the coveris placed over. each set 'of' sheets, the operator applies an exhaust device to the connection37, thus exhausting the :air from the space beneath the cover 34 and pressing such cover down tendency for them to move duringthe cycle This form of cover is somewhat easier V of operations. In order to still further thereof, a rib 43 (Fig. 6) is provided along one side of the platew2 for engaging the lower edges of the sheets. V

The use of the bath 8 of diethylene glycol above the mercury 7 is advantageous in that the liquid 8 prevents volatilization otthe mercury .with a consequent eliminationof its vapor poisoning effects. -.It also serves to wash the mercury from'theplates and chain while they are being pulled upward through the bath. The di'ethylene glycol is used because of its neutral character and high boiling point, but.- it .will be understood that any liquid mightbe substituted which had these characteristics. The diethylene glycol may be readily washed-off with water by the sprays. 14 and thecontainers then dried, the equipment: in this manner being keptcleanand dry for charging and recharging.- T he bath 8, being-unheated and subject to cooling by the incoming containers and plates, is maintained at a relatively lower temperature. than the mer cury bath 7 so that the containers and theircontents are not too rapidly heated when they enter the bath and have an opportunity to cool somewhat from their highest temperature before leaving the bath.

The avoidance of sprockets atthe lower ends of the chains 23' (Fig. 4) is, advanta-- geous as it permits of therreduc'tion of the cross section of the mercury chamber to a minimum, thus decreasing thecost of mercury which is a large item of expense. There, is considerable upthrust in the mercury bathagainst the chain and the containers due. to the difference in specific gravlty of these parts as compared with the mercury, but

this is offset by the: downward thrust due to the weight of the conveyor guided inthe members 21, 21 (Fig. 5), so that no diflicuL- ty is experiencedin moving the. chains and containers to the bottom of the mercury chamber.

A further feature 0f.

device is due to the fact that a progressively increasing pressure is applied to the plates as they move downward-through the diethylene glycol and mercury. This progressive pressure will tend to gradually force air outward from between the plates in an upward direction, thus doing away with the tendency to include trapped air between the plates which is encountered in the ordinary pressing operation. It will be understood that the purpose of the closure sheet 34 is to prevent application of the liquid in the joints between the sheets which would prevent proper compositing, and any other suitable means might beemployed which would accomplish this function. The use of advantage incidentv to the use of the mercurywell asa passing the sheet 34 for this purpose is preferred as it is easily applied'and removed andewhen the air is exhausted from beneath this sheet,

the pressure of the atmosphere tends to hold" the plates securely together and against movement without the use of additional holding means asheretofore. pointed out.v 1 The mercury may be drained from the mercury chamber when desired through the 7 outlet 44 (Fig. 2). Any mercurywhichli's carried along bycthe chains and containers and is not washed off in the bath-Bis caught in the drain pan 13 (Fig. l) and collected in the bottom of the cup 45. This may be withdrawn from time to time through the outlet: pipe 46. The diethylene :glycol which collects in the pan113 and e up 45.n1ay be removed through the connection 47 Fig. 8 illustrates a modified well construction' designed to permit the containers 2 and their contents to cool to a greater extent duringthe period of their upward movement;-

through the bath. To this end, theheating passages are provided. on one side of the Well onlyand extend onlypart way to the bottom of the well. On the other sideof the well the metal plate isexposed to the at mosphere to promote coolingofthe bath'an'd 'a. hollow partition 45 isprovided between the twosides of the we'll whi'ch reduces the' heat transmission from the hot side of the well to the cooler side. This arrangement permits the composited: plates to cool" down to a greater extent while still under; pressure, thus reducing the tendency to prothe plastic. v v

1. A process of compositing' glassand a reinforcing sheet, whieh consists in assem- 'ducebubbles between the glass sheetssand bling-a pair ofglass sheets with a reinforcing sheet therebetween with their opposing surfaces prepared for adhesion upon the application of heat and pressure, and 1noving the assembled sheet-s down into a heated bath of metal to a depth sufficient to COHlposite. thesheets by the pressure produced: in the bath by gravity, the edges of the, sheets being shielded. from contactwith the. bath during such movement into thesbath.

2. A process of compositing glass and pyroxylin plastic sheets which consists in assembling a pair of glass sheets with: a pyroxylin plastic sheet therebetween with their opposing surfacesprepared for adhe sion upon the application of heat andpressure, moving the sheets down into a heated bath of mercury to a depth sufficient to composite the sheets by the pressure produced in themercury by gravity, the edges ofthe,

sheets being shielded from contact with the mercury during said .movement into the llquid.

3. A process of composition glass and re inforcing-sheets, which con'sistsjn assembling a pair of glass sheets with a sheet of reinforcing material therebetween, placing.

the assembled sheets in a container having a flexible side and moving. the container down into a heated bath of metal to a depth suflicient to composite the sheets by the pressure produced in the liquid by gravity;

4. A process of compositing glass and reinforcing sheets, which conslsts 1n assembling a pair of glass sheets with a sheet of pyroXylin plastic and layers of cement there-- between, placingthe assembled sheets in a container having a flexible side, and moving the container down into a heated bath of mercury to a depth sufficient to composite the sheets by the'pressure produced in themercury by gravity.

5. In apparatus for making composite.

6. In apparatus for making composite glass from a plurality of sheets, a mercury bath, a bath of a liquid lighter than the mercury on top of the mercury bath, means for heating the mercury, a conveyor mov able down throughboth liquids to a depth sufficient to composite the, sheets by the hydrostatic pressure incident to gravity andv then upward out of the liquids and a flat containerfor the glass having a flexible side secured to the conveyor.

7. In apparatus for making composite.

glass from a plurality of sheets,:a mercury bath, means for heating such bath, arconveyormovable down into the bath to a depth suflicient to composite the sheets by the hydrostatic pressure incident to gravity and the-n out of the bath, a flat container secured to the conveyor having a removable rubber sheet constituting one side thereof and adapted to carry a plurality ofsheets to be composited, means for exhausting the air from the container, and means ing the conveyor.

8. In apparatus for making composite glass from a plurality of sheets, a mercury bath, means for heating such bath, an endior movless conveyor havinga horizontal flight and a vertical flight extending down into the bath to a depth sufficient to composite the sheets by the hydrostatic pressureincident to gravity and then out of the bath, a'flat container secured tothe conveyor having a flexible sideand adapted to carry a plurality of sheets to be composited, and means for moving the conveyor.

9. In apparatus for rigid S1616,

making a composite glass from a plurality of sheets, a liquid bath ofmetal, means for heating such bath, a conveyor movable down into the bath to a depth sufficient to composite the sheets by the hydrostatic pressure incident to gravity and then out of the bath, :a flat container secured to the conveyor havinga flexible side and: adapted to carry a plurality of sheets to be composited, and means for moving the conveyor. 1

1O. In apparatus'for making composite glass from a plurality of sheets, a mercury bath, means for heatingsuch bath, an endless conveyorhaving a'hori zontal flight and a vertical flight extending down into the bath to adepth sufficient to composite the sheets by: the hydrostatic pressure incident to gravity and then out of the bath, a series of containers secured to the conveyor each having a flexible side and. adapted to carry a plurality of'sheets to be composited and means formovinguthe conveyor to carry the containers through the bath oneafter the other. i 1

11. In apparatus for making composite glass froma plurality, of sheets, a mercury bath, means for heating such bath,an endless conveyor having a horizontal flight and a vertical fiight extending-down into the bath to. a depth sufficient to composite the sheets by the hydrostatic pressure incident to gravity. and then out of the bath, said conveyor comprisingapair of chains, a series of flat containers for. carrying the sheets tobe composited, each hinged at one'edge between-the chains soas to hang in vertical position during thetravel of the conveyor into andout-of the bath and each having a rubber sheet as the closure of one side of the container, and means for moving the on top of the mercury bath, means for heat ing the-mercury," a conveyor movable down through both liquids and then upward out ofthe liquid and a flat container for the sheets to be composited-securedto the conveyor andhaving a flexible side.

In testimonywhereof, I have hereunto subscribed my name this 7th day of July,

- JAMES H. SHEETS. 

